Because it's an example to counter your example. And it's clearly worked because the best thing you can come back with is "Sentomaru was too strong", which was my point to begin with, and his Haki isn't exactly impressive either.That's because the happened between Luffy and Sentomaru was too high. I don't know why you brought up him at all when there's a page right up above of Luffy about do what I said he did.
No it's not.
How does that not make sense? If Zoro was better than Sanji at both basic types of Haki then there's no point in considering Sanji a member of the M3 since he already has him beat in strength before they even learnt Haki, we've seen him use his Kenbunshoku Haki to great effect bach in Punk Hazard, Zoro? Nope. He's not done anything remotely impressive with Kenbunshoku Haki.